Currently, there are two general techniques for drilling holes in a multi-material stack-up, or an assembly made of two or more layers of different materials. In one technique, holes are drilled in the layers of the stack-up while the layers are separated from each other. For instance, one hole is drilled in a first layer, and a corresponding hole is drilled in a second layer. The layers are then assembled together with the holes lining up together. However, due to the holes being drilled in the layers individually, rather than through the layers jointly, errors may occur with an alignment, a size, and an orientation of the holes when the layers are assembled together.
In the second technique called match drilling, one hole may be drilled through the stack-up while the layers are held together. More specifically, the layers may be assembled and joined together first, then a hole may be drilled through the entire stack-up. Although problems of hole alignment, sizing, and orientation are eliminated, match drilling may still result in imperfect holes. For example, match drilling can create burrs on metal corners and can produce tear-out in carbon fiber reinforced polymer material.
In order to clean up the holes after match drilling, the stack-up is disassembled, and the holes in each layer undergo a finishing process. Following the finishing process, the layers are reassembled to form the stack-up. The need to assemble, disassemble, and reassemble the stack-up in order to achieve high quality holes results in a significant increase in cost and flow time during production. Accordingly, there is a need to provide a cost-effective, efficient method and system for machining a multi-material stack-up.